The present invention relates to a fluidised bed waste water reactor and more particularly to such a reactor having novel features which facilitate operation and maintainance of the reactor.
Fluidised bed waste water reactors are known in which a bed of particulate matter such as sand is fluidised in a reactor tank by the upward flow of the waste water. The tank is seeded with a suitable bacterial population which attaches itself to the sand particles and grows thereon. In practice difficulty is experienced in obtaining and maintaining a stable fluidising flow of waste water to maintain the bed of sand particles in a fluidised state. It has been considered desirable when designing fluidised bed reactors to keep the ducting for recycling the waste water through the bed wholly within the reactor tank (see Australian Patent Specification No. 84684/82). This approach means that the distribution pipes are wholly within the reactor tank and therefore difficult to clean in the event that they become blocked. As the difficulties in obtaining and maintaining an evenly fluidised bed is in part caused by blocking of the orifices in the distribution pipes the difficulty in cleaning the pipes is a severe handicap. The present invention provides an arrangement which overcomes this known difficulty and also, independently, introduces a number of innovations in the design of fluidised bed reactors.